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Asian Gypsy Moth

Temperature Effects on Asian Gypsy Moth Development and Survival

Research Issue

[photo:] Asian gypsy moth molting.A phenology model exists for North American gypsy moth but the growth parameters needed to modify the model to predict development of strains from other world areas was not available. The ability to accurately predict larval instar is critical for timing control or eradication treatments.  Also, knowing when adults will be flying is important to timing mating disruption treatments and pheromone trap deployment. We also do not know how long newly hatched larvae can survive without food should they hatch on a ship or its cargo. Survival of newly hatched larvae under different temperatures will help predict their ability to establish in new areas, especially if they hatch asynchronously with the hosts they can utilize for development.

Our Research

We reared eight geographical populations (six from the asiactica subspecies and two from the japonica subspecies) of Asian gypsy moth on artificial diet at five constant temperatures (10-30°C) to quantify the effects of temperature on the developmental rate of the larvae and determine degree-day requirements for each instar and stage. The data obtained from this study is being used to develop a phenology model for Asian gypsy moth and to parameterize existing North American gypsy moth models.

The survival and development of newly hatched Lymantria larvae from nine geographic populations at seven temperatures (1–30°C) held without food, with summer foliage of a preferred or conifer host was determined.

Expected Outcomes

Biological basis for modifying the gypsy moth phenology model to accurately predict development of strains from other world areas.

Research Results

Key findings: There is substantial variation in the growth rates of gypsy moth larvae of Asian origins and survival of newly hatched larvae held without food declined from about a month at 5°C to a few days at 30°C.

Growth rates varied between gypsy moth strains; strains from higher latitudes or colder climates compensated for the shorter growing season by completing their development faster. The number of larval instars that different strains went through also varied.  Strains that developed faster had fewer larval instars and the adults were larger. A possible explanation for these differences is that over time the local climate of an area has selected for individuals that will survive and reproduce best in that area. In areas with shorter growing seasons faster growth may be essential whereas in warmer areas protracted development could occur. Generation to generation changes in growth rate also could occur based on weather conditions, food availability and quality, and maternal nutrition. 

[photo:] Researchers making daily observations to determine survival and days in each instar/stage for individual Asian gypsy moths reared on artificial diet.Larval developmental rate increased with temperature until it reached an optimum at 29 °C. Larvae experienced significant molting problems at the highest and lowest temperatures tested (10 and 30 °C), and at 30 °C fecundity and fertility were significantly reduced. These findings suggest that development and survival of Asian gypsy moth may be limited by summer temperature extremes in the Southern United States. We selected the strain that grew the fastest, one from Siberian Russia, and the one that grew the slowest, one from Beijing China, to develop degree day information for the range of observed variation in developmental rate. It took between 69 and 79 degree days for 10% and 101-150 degree days for 90% of the Asian gypsy moth larvae to reach the second instar. After 564 to 858 degree days 10% of the adult males would be flying and after 706 to 1084 degree days 90% would be flying. This information can be used to predict the timing for both bio-pesticide application (second instars) and adult trapping (males). Our data will benefit pest managers in developing management strategies, pest risk assessments, and timing for implementation of management tactics.

[photo:] Asian gypsy moth larva in petri dish.There was considerable variation both within and among the Lymantria populations in the survival of larvae at different temperatures when held with and without food. Without food survival declined from about a month at 5°C to a few days at 30°C, following a typical enzymatic kinetic rate function. At 1°C larval survival was less than at 5°C likely because the larvae were susceptible to freezing. Larvae from the one L. monacha population fed and gained weight on the summer foliage, particularly on the conifer, at 10–15°C but < 20% survived for 14 d at 20–30°C. The newly hatched L. dispar larvae from all eight populations fed (at 10–30°C) and developed (at 15–30°C) on the summer foliage of one or both of the hosts. This suggests that they may be able to find adequate food for establishment even if hatch is not synchronous with bud break in the invaded habitat. Survival on the conifer was highest for one Chinese and two European populations of L. dispar, suggesting the ability to utilize conifers is population and not subspecies specific.

Keena, Melody A; Shi, Juan. 2019. Effects of Temperature on First Instar Lymantria (Lepidoptera: Erebidae) Survival and Development With and Without Food. Environmental Entomology. 48(3): 655-666. https://doi.org/10.1093/ee/nvz028. .

Limbu, Samita; Keena, Melody; Chen, Fang; Cook, Gericke; Nadel, Hannah; Hoover, Kelli 2017. Effects of temperature on development of Lymantria dispar asiatica and Lymantria dispar japonica (Lepidoptera: Erebidae). Environmental Entomology. 46(4): 1012-1023. https://doi.org/10.1093/ee/nvx111.

Research Participants

Principal Investigators

  • Melody Keena, USDA Forest Service, Northern Research Station, Research Entomologist
  • R. Talbot Trotter III, USDA Forest Service, Northern Research Station, Research Ecologist
  • Samita Limbu, The Pennsylvania State University, Department of Entomology, previous doctoral student
  • Fang Chen, Forestry Bureau of Jingzhou, China
  • Gericke Cook, USDA Animal and Plant Health Inspection Service, PPQ CPHST, Fort Collins, CO
  • Hannah Nadel, USDA Animal and Plant Health Inspection Service, PPQ S & T, Buzzards Bay, MA
  • Kelli Hoover, The Pennsylvania State University, Department of Entomology
  • Last modified: May 18, 2020